I've been reading this Wikipedia - Electrical Load topic and there is a section which is confusing me... So what you do is go to the "A more technical approach" section in this topic and then read the 4th line which starts with "With no load (open-circuited terminals)...".
Now the line says that "With no load (open-circuited terminals), all of Vs falls across the output; the output voltage is Vs." But how? Isn't there be a voltage drop across the resistor Rs? If not, why not?